<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    #neon-btn {
      display: flex;
      align-items: center;
      justify-content: space-around;
      background: #031628;
      width: 50%;
      height: 500px;
    }

    .btn {
      border: 1px solid;
      background-color: transparent;
      text-transform: uppercase;
      font-size: 14px;
      padding: 10px 20px;
      font-weight: 300;
    }

    .one {
      color: #4cc9f0;
    }

    .two {
      color: #f038ff;
    }

    .three {
      color: #b9e769;
    }

    .btn:hover {
      color: white;
      border: 0;
    }

    .one:hover {
      background-color: #4cc9f0;
      -webkit-box-shadow: 10px 10px 99px 6px rgba(76, 201, 240, 1);
      -moz-box-shadow: 10px 10px 99px 6px rgba(76, 201, 240, 1);
      box-shadow: 10px 10px 99px 6px rgba(76, 201, 240, 1);
      transition: all ease-in 0.5s;
    }

    .two:hover {
      background-color: #f038ff;
      -webkit-box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
      -moz-box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
      box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
      transition: all ease-in 0.5s;
    }

    .three:hover {
      background-color: #b9e769;
      -webkit-box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
      -moz-box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
      box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
      transition: all ease-in 0.5s;
    }
  </style>
</head>

<body>
  <div id="neon-btn">
    <button class="btn one">Hover me</button>
    <button class="btn two">Hover me</button>
    <button class="btn three">Hover me</button>
  </div>
</body>

</html>